BELFAST, United Kingdom: Fifteen police officers were hurt in violence which flared in Northern Ireland overnight when 1,000 protesters rioted after councillors voted not to fly the British flag all year round, police said Tuesday.Two security workers and a press photographer were also injured Monday night as officers were pelted with bricks, bottles and fireworks and demonstrators tried to force their way into City Hall in Belfast.Trouble broke out minutes after Belfast city councillors voted to remove the Union Flag from City Hall, meaning it will be taken down for the first time since the building opened in 1906.Nationalists opposed to Northern Ireland being part of the United Kingdom wanted the flag taken down permanently, but in a compromise it will now be flown only on 17 designated days.At one point, Loyalists with scarves tied around their heads to conceal their identity tried to kick down the back door of City Hall to gain entry.Northern Ireland’s First Minister Peter Robinson said the violence was unacceptable.“There is no excuse or justification for attacks on police officers, council staff, and property,” he said.“Such behavior is not representative of those who campaigned to maintain the Union Flag flying over Belfast City Hall.”Unionist parties who support Northern Ireland retaining its links to Britain share power with Nationalists in the provincial assembly.The assembly was set up under a 1998 peace deal that largely ended three decades of sectarian violence in Northern Ireland in which more than 3,600 people died.Mike Nesbitt, the leader of the Ulster Unionist Party, said that while he condemned the violence, the flag vote showed that Unionists feel they are being marginalized.“Firstly, we are clear that no one should have been attacked or injured last night, no property should have been damaged, and no illegality should be tolerated. Attacking police officers is wrong, full-stop,” he told the BBC.“But it is also wrong to continue to make the Unionist people of Belfast feel that they are to be treated as a minority whose heritage and values are to be suppressed.”